The present invention generally relates to test evaluations of hydrophones in a line array under different flow conditions and particularly an apparatus which simulates the water flow conditions which are prevalent at sea when an acoustic line array is towed therethrough.
In most underwater acoustic detection systems subject to flow, the flow is characteristically turbulent resulting in a locally very intense fluctuating pressure field on the surface of the structure surrounding the acoustic sensors. In the case of cylindrical line arrays of large length-to-diameter ratio, the typical lengths are so large as to preclude flow testing in conventional wind or water tunnels. Furthermore, few flow facilities are acoustically quiet enough to permit evaluation of the acoustic response of line arrays under various flow conditions. While tests have been conducted on simulated short lengths of cylindrical line arrays in conventional types of flow facilities, such tests are costly and depend on very critical care in setting up the experiment and are very limited in the sense of the length and diameter of the array segment under test. As much as the actual modules of line array cannot be accommodated in existing test facilities, at-sea testing has heretofore always been required to evaluate towed line array performance. It is thus desirable to have a simple system to evaluate towed line array performance and which can simulate different turbulent conditions to which a line array at sea is subjected to.